/* ExplainTime EDU · site styles */
:root {
  --blue: #2E6CC4;
  --blue-light: #5B9CF0;
  --blue-dark: #1F529E;
  --ink: #16223A;
  --ink-soft: #4A5670;
  --page: #FFFFFF;
  --panel: #F2F5FA;
  --line: #DCE3EE;
  --mosaic: #EFE6D3;
  --mosaic-grout: #E2D5BC;
  --roman-red: #8E2A23;
  --link: #2E6CC4;
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display", "Helvetica Neue", Helvetica, Arial, sans-serif;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ink: #EEF2F8;
    --ink-soft: #A9B4C7;
    --page: #0E1626;
    --panel: #172238;
    --line: #26334D;
    --link: #7FB2F5;
  }
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: var(--font);
  font-size: 1.0625rem;
  line-height: 1.55;
  padding-bottom: env(safe-area-inset-bottom, 0px);
}

img { max-width: 100%; height: auto; display: block; }

a { color: var(--link); text-underline-offset: 0.15em; }

a:focus-visible, summary:focus-visible, .button:focus-visible {
  outline: 3px solid var(--blue-light);
  outline-offset: 3px;
  border-radius: 6px;
}

.wrap { width: min(1120px, 100% - 3rem); margin-inline: auto; }

/* ---------- header ---------- */
.site-header {
  padding-top: env(safe-area-inset-top, 0px);
  border-bottom: 1px solid var(--line);
}
.site-header .wrap {
  display: flex; align-items: center; justify-content: space-between;
  gap: 1rem; min-height: 4rem;
}
.brand {
  display: inline-flex; align-items: center; gap: 0.6rem;
  color: var(--ink); text-decoration: none; font-weight: 700; font-size: 1.125rem;
  letter-spacing: -0.01em;
}
.brand img { width: 32px; height: 32px; border-radius: 8px; }
.site-nav { display: flex; gap: 1.5rem; }
.site-nav a { color: var(--ink-soft); text-decoration: none; font-weight: 500; }
.site-nav a:hover, .site-nav a[aria-current="page"] { color: var(--ink); }

/* ---------- hero ---------- */
.hero { padding: 4.5rem 0 2.5rem; }
.hero h1 {
  font-size: clamp(2.6rem, 6.4vw, 4.75rem);
  line-height: 1.02; letter-spacing: -0.035em; font-weight: 800;
  margin: 0 0 1.25rem; max-width: 12ch;
}
.hero .lede { font-size: clamp(1.125rem, 2vw, 1.3rem); color: var(--ink-soft); max-width: 34rem; margin: 0 0 2rem; }
.cta-row { display: flex; flex-wrap: wrap; align-items: center; gap: 0.75rem 1.25rem; }
.button {
  display: inline-block; background: var(--blue); color: #fff; text-decoration: none;
  font-weight: 600; padding: 0.85rem 1.4rem; border-radius: 999px;
}
.button:hover { background: var(--blue-dark); }
.cta-note { color: var(--ink-soft); font-size: 0.95rem; }

/* ---------- to-scale timeline band (the signature element) ---------- */
.band {
  --tile: 14px;
  background-color: var(--mosaic);
  background-image:
    linear-gradient(var(--mosaic-grout) 1px, transparent 1px),
    linear-gradient(90deg, var(--mosaic-grout) 1px, transparent 1px);
  background-size: var(--tile) var(--tile);
  color: #16223A;
  position: relative;
}
.band::before, .band::after {
  content: ""; display: block; height: 14px;
  background: repeating-linear-gradient(90deg, var(--roman-red) 0 10px, transparent 10px 14px);
  opacity: 0.85;
}
.band-inner { padding: 2.5rem 0 2rem; }
.scroller { overflow-x: auto; -webkit-overflow-scrolling: touch; padding-bottom: 0.5rem; }
.timeline {
  position: relative; min-width: 960px; height: 360px; margin: 0 auto;
}
.axis {
  position: absolute; left: 0; right: 0; top: 50%; height: 4px; margin-top: -2px;
  background: #FFFFFF; border-radius: 2px; box-shadow: 0 0 0 1px rgba(22, 34, 58, 0.08);
}
.tick {
  position: absolute; top: 50%; width: 2px; height: 14px; margin: -7px 0 0 -1px;
  background: rgba(22, 34, 58, 0.25);
}
.tick span {
  position: absolute; top: 18px; left: 50%; transform: translateX(-50%);
  font-size: 0.72rem; font-weight: 600; color: rgba(22, 34, 58, 0.55); white-space: nowrap;
  background: var(--mosaic); padding: 0 4px; z-index: 1;
}
.tick { z-index: 1; }
.scroll-hint { display: none; margin: 0 0 0.75rem; font-size: 0.9rem; font-weight: 600; color: #3D4A63; }
@media (max-width: 1000px) { .scroll-hint { display: block; } }
.event { position: absolute; left: var(--x); top: 50%; }
.event .dot {
  position: absolute; width: 18px; height: 18px; margin: -9px 0 0 -9px; border-radius: 50%;
  background: var(--blue); border: 3px solid #fff; box-shadow: 0 1px 3px rgba(22, 34, 58, 0.3);
}
.event .stem { position: absolute; left: -1px; width: 2px; background: #fff; }
.event .card {
  position: absolute; width: 158px; padding: 0.55rem 0.7rem;
  background: rgba(255, 255, 255, 0.92); border-radius: 12px;
  box-shadow: 0 6px 18px rgba(22, 34, 58, 0.12);
  transform: translateX(-50%);
  font-size: 0.82rem; line-height: 1.3;
}
.event .card b { display: block; color: var(--blue); font-size: 0.78rem; margin-bottom: 0.15rem; }
.event.up .stem { bottom: 0; height: var(--h); }
.event.up .card { bottom: var(--h); }
.event.down .stem { top: 0; height: var(--h); }
.event.down .card { top: var(--h); }
.event.edge-right .card { transform: translateX(-88%); }
.event.edge-left .card { transform: translateX(-12%); }
.band-caption { max-width: 46rem; margin: 1.25rem 0 0; font-size: 0.98rem; color: #3D4A63; }

@media (prefers-reduced-motion: no-preference) {
  .event { animation: rise 0.5s ease-out both; animation-delay: calc(var(--i) * 90ms + 150ms); }
  @keyframes rise { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
}

/* ---------- sections ---------- */
section.block { padding: 4.5rem 0; }
section.block + section.block { border-top: 1px solid var(--line); }
h2 { font-size: clamp(1.8rem, 3.6vw, 2.5rem); letter-spacing: -0.025em; line-height: 1.1; margin: 0 0 0.75rem; }
h3 { font-size: 1.2rem; letter-spacing: -0.01em; margin: 0 0 0.4rem; }
.intro { color: var(--ink-soft); max-width: 40rem; margin: 0 0 2.75rem; }

.steps { list-style: none; margin: 0; padding: 0; display: grid; gap: 2.5rem; grid-template-columns: repeat(3, 1fr); counter-reset: step; }
.steps li { counter-increment: step; }
.steps figure { margin: 0 0 1.25rem; }
.steps img { border-radius: 28px; border: 1px solid var(--line); width: 100%; max-width: 300px; }
.steps h3::before {
  content: counter(step); display: inline-grid; place-items: center;
  width: 1.7rem; height: 1.7rem; margin-right: 0.55rem; border-radius: 50%;
  background: var(--blue); color: #fff; font-size: 0.9rem; vertical-align: 0.1em;
}
.steps p { margin: 0; color: var(--ink-soft); max-width: 30ch; }

.features { display: grid; grid-template-columns: 1.1fr 1fr; gap: 3rem; align-items: start; }
.feature-list { display: grid; grid-template-columns: 1fr 1fr; gap: 2rem 2.25rem; margin: 0; }
.feature-list dt { font-weight: 700; font-size: 1.05rem; margin-bottom: 0.3rem; }
.feature-list dd { margin: 0; color: var(--ink-soft); font-size: 0.98rem; }
.features figure { margin: 0; }
.features img { border-radius: 18px; border: 1px solid var(--line); }
.features figcaption { color: var(--ink-soft); font-size: 0.9rem; margin-top: 0.6rem; }

.gallery { display: grid; grid-template-columns: repeat(2, minmax(0, 260px)); gap: 1.5rem; }
.gallery img { border-radius: 26px; border: 1px solid var(--line); }
.split { display: grid; grid-template-columns: 1fr auto; gap: 3rem; align-items: center; }

.privacy-band { background: var(--panel); }
.privacy-band p { max-width: 40rem; color: var(--ink-soft); }

/* ---------- document pages (support, privacy) ---------- */
.doc { padding: 3.5rem 0 4.5rem; }
.doc .wrap { max-width: 46rem; }
.doc h1 { font-size: clamp(2.2rem, 5vw, 3.2rem); letter-spacing: -0.03em; line-height: 1.05; margin: 0 0 0.75rem; }
.doc h2 { font-size: 1.45rem; margin: 2.5rem 0 0.6rem; }
.doc .updated { color: var(--ink-soft); margin: 0 0 2rem; }
.contact {
  border: 1px solid var(--line); border-radius: 16px; padding: 1.25rem 1.4rem; margin: 1.75rem 0 2.5rem;
  background: var(--panel);
}
.contact p { margin: 0.25rem 0; }
.contact .email { font-size: 1.15rem; font-weight: 600; }
details { border-bottom: 1px solid var(--line); }
details:first-of-type { border-top: 1px solid var(--line); }
summary {
  cursor: pointer; list-style: none; padding: 1rem 2rem 1rem 0; font-weight: 600; position: relative;
}
summary::-webkit-details-marker { display: none; }
summary::after {
  content: "+"; position: absolute; right: 0.25rem; top: 0.85rem; font-size: 1.35rem; font-weight: 400; color: var(--ink-soft);
}
details[open] summary::after { content: "–"; }
details p { margin: 0 0 1.1rem; color: var(--ink-soft); }

/* ---------- footer ---------- */
.site-footer { border-top: 1px solid var(--line); padding: 2rem 0 2.5rem; color: var(--ink-soft); font-size: 0.92rem; }
.site-footer .wrap { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 1rem; }
.site-footer nav { display: flex; gap: 1.25rem; }
.site-footer a { color: var(--ink-soft); }

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .steps { grid-template-columns: 1fr; gap: 3rem; }
  .steps img { max-width: 280px; }
  .features, .split { grid-template-columns: 1fr; }
}
@media (max-width: 560px) {
  .feature-list { grid-template-columns: 1fr; }
  .gallery { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; }
  .site-nav { gap: 1rem; }
  .hero { padding-top: 3rem; }
}